This invention relates to a unique brake lining wear indicator to be supported on a brake shoe backing plate of a drum brake assembly.
Drum brakes are widely used in vehicle braking systems. In a typical drum brake, two arcuate brake shoe assemblies are located inside a rotating cylindrical brake drum. Each brake shoe assembly includes a backing plate which carries brake lining friction material. A brake actuator moves the brake shoe assemblies toward the rotating brake drum such that the brake lining friction material contacts the inner surfaces of the drum, thus retarding the rotation of the drum. Over a period of time, the contact between the lining and the drum causes the lining to wear. If the lining becomes too thin, ineffective braking can occur. Thus, it is desirable to provide an indication when brake lining thickness is such that the brake shoes should be changed.
Several problems arise when trying to determine whether the brake linings have sufficiently worn such that they need to be changed. Often the wheel and the brake drum have to be removed from the vehicle for the brake lining thickness to be measured. This is cumbersome and time consuming. Thus, it is desirable to have an efficient way to visually inspect the lining thickness to determine whether the brake linings need to be replaced without having to physically measure the linings.
Brake lining wear indicators have been used as visual inspection tools in the prior art. Typically, these indicators have been incorporated into the lining material itself Notches have been put into the sides of the lining material to visually signal when the linings need to be changed. Also, colored material has been inserted into the brake lining material at a predetermined height to serve as a visual indication to change the brake linings. These prior art systems have required modification of the lining material, which is undesirable. Thus, it is desirable to have a visually detectable brake lining indicator which can be easily attached to the brake shoe assembly and which is not incorporated into the lining material.